Regulator circuit and method of operating regulator circuit

ABSTRACT

A regulator circuit includes a regulator output node, at least (N+1) regulator control circuits, and N drivers. N is an integer greater than 1. Each one of the N drivers includes a multiplexer, a driver stage, and a pre-driver stage. The multiplexer includes an input port and an output port, where the input port of the multiplexer is coupled with output nodes of the at least (N+1) regulator control circuits. The driver stage is coupled with the regulator output node. The pre-driver stage is configured to control the driver stage based on a signal on the output port of the multiplexer.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. Technological advances in IC materials and design have producedgenerations of ICs where each generation has smaller and more complexcircuits than the previous generation. In the course of integratedcircuit evolution, functional density (i.e., the number ofinterconnected devices per chip area) has generally increased whilegeometry size (i.e., the smallest component or line that can be createdusing a fabrication process) has decreased. The ICs have been applied invarious electronic devices, and an external voltage received by theelectronic devices is usually different than that for operating the ICsof the electronic devices. For example, in some applications, a mobiledevice receives a 3.6 V power from a battery while the ICs of the mobiledevice operate at a voltage level ranging from 1.8 V to 0.9 V. Moreover,in some applications, an IC receives a power supply voltage andinternally operating logic circuit therein at a lower voltage level inorder to obtain higher operation speed and lower power consumption. Inthese circumstances, direct current (DC) to DC (DC-DC) regulators areusable to convert one DC voltage level to another.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a functional block diagram of a regulator circuit inaccordance with some embodiments.

FIG. 2 is a circuit diagram of a portion of a regulator circuit inaccordance with some embodiments.

FIG. 3 is a timing diagram of logical values and waveforms at variousnodes of a regulator circuit in accordance with some embodiments.

FIG. 4A is a graph of waveforms of various currents provided bydifferent drivers of a regulator circuit in accordance with someembodiments.

FIG. 4B is a graph of waveforms of various currents provided bydifferent drivers of a regulator circuit having a configurationdifferent from some embodiments of the present disclosure.

FIG. 5 is a flow chart of a method of operating a regulator circuit inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

In some embodiments, a regulator circuit includes N driverscorresponding to N different phases and (N+1) regulator control circuitsconfigured to generate N control signals corresponding to N differentphases. By rotating the combinations of the N drivers and (N+1)regulator control circuits, the phase errors among control signalscaused by mismatch or process variations of (N+1) regulator controlcircuits are evenly distributed to the N drivers in a time-averagedmanner. As a result, the N drivers share the loading evenly and havebalanced output currents.

FIG. 1 is a functional block diagram of a regulator circuit 100 inaccordance with some embodiments. Regulator circuit 100 includes a firstpower supply node 102, a second power supply node 104, a regulatoroutput node 106, N drivers 110[1], 110[2], 110[3], . . . , 110[N]coupled with regulator output node 106 and powered by a power domaindefined by first and second power supply nodes 102 and 104, at least(N+1) regulator control circuits 120[1], 120[2], 120[3], 120[4], . . . ,120[N+1] coupled with N drivers 110[N:1], and a task controller 130coupled with N drivers 110[N:1] and at least (N+1) regulator controlcircuits 120[(N+1):1]. Regulator circuit 100 further includes an erroramplifier 140 between regulator output node 106 and at least (N+1)regulator control circuits 120[(N+1):1] and a capacitive device 150between regulator output node 106 and second power supply node 104. Aload 160 is coupled with regulator output node 106. Load 160 is not partof regulator circuit 100.

First power supply node 102 is configured to carry a voltage VDD. Secondpower supply node 104 is configured to carry a voltage VSS. In someembodiments, voltage VSS has a voltage level usable as a groundreference level of regulator circuit 100, and voltage VDD has a voltagelevel also being referred to as a supply voltage level. In someembodiments, the ground reference level is lower than the supply voltagelevel. In some embodiments, if the ground reference level is used todefine the voltage level of 0 V, the power supply voltage level rangesfrom 1.2 V to 2.5 V.

Regulator circuit 100 is configured to generate a regulated DC voltageVOUT at regulator output node 106 for driving load 160. In someembodiments, voltage VOUT has a voltage level between the power supplyvoltage level and the ground reference level. In some embodiments, ifthe ground reference level is used to define the voltage level of 0 V,the voltage level of voltage VOUT ranges from 30% to 70% of the powersupply voltage level.

Drivers 110[N:1] are configured to provide corresponding currents I[1],I[2], I[3], . . . , I[N] to regulator output node 106 and then to load160. Each one of drivers 110[N:1] is configured to receive (N+1) controlsignals CTRL[1], CTRL[2], CTRL[3], CTRL[4], . . . , CTRL[N+1] fromregulator control circuits 120[(N+1):1] and a corresponding one set ofselection signals SEL[1], SEL[2], SEL[3], . . . , SEL[N] from taskcontroller 130. Regulator control circuits 120[1] ˜120[N+1] areconfigured to generate corresponding control signals CTRL[(N+1):1].

Regulator control circuits 120[(N+1):1] are configured to receive anerror signal VE from error amplifier 140, a clock signal CLK, and (N+1)sets of phase control signals PH[1], PH[2], PH[3], PH[4], . . . ,PH[N+1]. Each regulator control circuit 120[(N+1):1] is configured togenerate a corresponding control signals CTRL[(N+1):1] based on theclock signal CLK, the error signal VE, and a corresponding set of phasesignals PH[(N+1):1]. Task controller 130 receives the clock signal CLKand is configured to set each one of regulator control circuits120[(N+1):1] to generate a control signal CTRL[(N+1):1] corresponding toN different phases in a rotational manner. In some embodiments, the Nphases are defined based on a frequency and a phase of the clock signalCLK. Also, at any given time during the operation of regulator circuit100, N regulator control circuits of regulator control circuits120[(N+1):1] are configured to variously generate N control signalscorresponding to N different phases.

Task controller 130 is further configured to set the drivers 110[N:1]such that a p-th driver 110[p] is operated based on control signalscorresponding to a p-th phase of the N different phases from theregulator control circuits 120[(N+1):1] in a rotational manner, wherethe index “p” is an integer ranging from 1 to N. Thus, at any given timeduring the operation of regulator circuit 100, the p-th driver 110[p] isconfigured to provide the p-th current I[p] to the regulator output node106 based on a control signal of the N control signals that correspondsto the p-th phase, e.g., CTRL[p] among CTRL[N:1] from regulator controlcircuits 120[N:1].

In addition, task controller 130 is configured to set another regulatorcontrol circuit, e.g., regulator control circuit 120[N+1], to generateanother control signal CTRL[N+1] corresponding to the p-th phase of theN different phases. Task controller 130 is also configured to set thep-th driver 110[p] to provide the p-th current I[p] based on the anothercontrol signal CTRL[N+1] in place of the control signal CTRL[p], whichcorresponds to the p-th phase and is currently used by the p-th driver110[p]. In some embodiments, the rotation of the combinations of usingregulator control circuits 120[(N+1):1] for N different phases includesreplacing one of working regulator control circuits with an idleregulator control circuit during each clock cycle of clock signal CLK.

Error amplifier 140 has a non-inverted input 142 configured to receive areference voltage VREF, an inverted input 144 configured to receive afeedback voltage VFB, and an output 146. Error amplifier 140 isconfigured to generate error signal VE at the output 146 based on avoltage level of feedback voltage VFB and a reference voltage level ofreference voltage VREF. In some embodiments, a voltage level of feedbackvoltage VFB equals the voltage level of the voltage VOUT at theregulator output node 106. In some embodiments, regulator circuit 100further includes a voltage divider (not shown) configured to convert avoltage level of voltage VOUT to a voltage level of feedback voltage VFBby a predetermined ratio. In some embodiments, voltage VREF has avoltage level between the power supply voltage level and the groundreference level.

Capacitive device 150 functions as a low-pass filter to stabilizevoltage VOUT. Electrical characteristics of capacitive device 150 arerepresented by an equivalent series capacitance (depicted as a capacitor152) and an equivalent series resistance (ESR, depicted as a resistor154).

Details regarding drivers 110[N:1], regulator control circuits120[(N+1):1], and task controller 130 are further illustrated inconjunction with FIGS. 2 and 3.

FIG. 2 is a circuit diagram of a portion of regulator circuit 100, withfurther details of one driver 110[p] and one regulator control circuit120[q], in accordance with some embodiments. The index “q” is an integerranging from 1 to (N+1). Drivers 110[N:1] other than driver 110[p] arecorrectively represented by box 110[x], and regulator control circuits120[(N+1):1] other than regulator control circuit 120[q] arecorrectively represented by box 120[x]. Other components in FIG. 2 thatare the same or similar to those in FIG. 1 are given the same referencenumbers, and detailed description thereof is thus omitted.

Driver 110[p] includes a multiplexer 212 coupled with regulator controlcircuits 120[q] and 120[x] (i.e., regulator control circuits120[(N+1):1]), a pre-driver stage 214 coupled with multiplexer 212, adriver stage 214 coupled between pre-driver stage 214 and regulatoroutput node 106, and an inductive device 218 between driver stage 214and regulator output node 106. Driver 110[p] is configured to provide acurrent I[p] to regulator output node 106.

Multiplexer 212 includes an input port 212 a and an output port 212 b.Input port 212 a of multiplexer 212 is coupled with the output nodes 222of regulator control circuits 120[(N+1):1] and configured to receivecontrol signals CTRL[(N+1):1]. Responsive to selection signal SEL[p]from task controller 130, multiplexer 212 is set to couple the one ofcontrol signals CTRL[(N+1):1] corresponding to the p-th phase of Ndifferent phases with the output port of multiplexer 212, such ascoupling control signal CTRL[q] from regulator control circuit 120[q]with the output port of multiplexer 212. As a result, driver 110[p] isset by task controller 130 to operate based on the control signal at theoutput port of multiplexer 212.

Pre-driver stage 214 is configured to generate control signals DU and DLin order to control the driver stage based on a signal on the outputport 212 b of the multiplexer 212. Driver stage 216 includes an upperdriver 216 a, a lower driver 216 b, and an output node 216 c betweenupper driver 216 a and a lower driver 216 b. Upper driver 216 a is aP-type transistor coupled between output node 216 c of driver stage 216and first power supply node 102. Lower driver 216 b is an N-typetransistor coupled between output node 216 c of driver stage 216 andsecond power supply node 104. In some embodiments, control signals DUand DL turns on one of the upper driver 216 a or 216 b in order toinject or withdraw current into or from regulator output node responsiveto the control signal at the output port of multiplexer 212.

Moreover, inductive device 218 is between output node 216 c of thedriver stage 216 and the regulator output node 106. Inductive device218, together with capacitive device 150, functions as a low-pass filterto stabilize voltage VOUT.

In some embodiments, each drivers 110[x] have a configuration equivalentto that of driver 110[p]. In some embodiments, drivers 110[x] and driver110[p] (i.e., drivers 110[N:1]) are fabricated based on a common circuitschematic.

Regulator control circuit 120[q] includes output node 222, a rampgenerator 224, and a comparator 226 coupled between output node 222 ofregulator control circuit 120[q] and ramp generator 224. Ramp generator224 is configured to receive clock signal CLK and a set of phase controlsignals PH[q] from task controller 130, and to generate a ramp signalVRAMP. Ramp signal is a triangular wave signal or a saw-tooth wavesignal having one of the N different phases as designated by taskcontroller 130 through phase control signal PH[q]. Comparator 226 isconfigured to generate a control signal CTRL[q] by comparing the rampsignal VRAMP and error signal VE generated based on a voltage level atthe regulator output node 106 and a voltage level of reference voltageVREF. As such, control signal CTRL[q] is a pulse width modulation PWMsignal corresponding to a phase of ramp signal VRAMP designated by taskcontroller 130.

In some embodiments, each regulator control circuits 120[x] have aconfiguration equivalent to that of regulator control circuit 120[q]. Insome embodiments, regulator control circuits 120[x] and regulatorcontrol circuit 120[q] (i.e., regulator control circuits 120[(N+1):1])are fabricated based on a common circuit schematic.

FIG. 3 is a timing diagram of logical values and waveforms at variousnodes of a regulator circuit, such as regulator circuit 100 when N isset to be four (4), in accordance with some embodiments. Waveforms310[1] ˜310[5] variously represent the waveforms of ramp signals VRAM ofregulator control circuits 120[1] ˜120[5]. In this embodiment, rampsignals VRAM of regulator control circuits 120[1] ˜120[5] are saw-toothwaveform signals. Equivalent decimal values 320[1] ˜320[4] variouslyrepresent the values of various sets of selection signals SEL[4:1].Waveform 330 represents the waveform of clock signal CLK. Taskcontroller 130 is configured to activate an idle regulator controlcircuit in place of a working regulator control circuit during eachclock cycle of clock signal CLK.

For example, at time T0, regulator control circuit 120[1] is set togenerate a ramp signal 310[1] having a phase being used to define the0-degree phase; regulator control circuit 120[2] is set to generate aramp signal 310[2] having a 90-degree phase; regulator control circuit120[3] is set to generate a ramp signal 310[3] having a 180-degreephase; regulator control circuit 120[4] is set to be idle; and regulatorcontrol circuit 120[5] is set to generate a ramp signal 310[5] having a270-degree phase. Also, the value of selection signal SEL[1] is set to‘1’ (320[1]) to couple control signal CTRL[1] from regulator controlcircuit 120[1] to pre-driver stage 214 of driver 110[1]; selectionsignal SEL[2] is set to ‘2’ (320[2]) to couple control signal CTRL[2]from regulator control circuit 120[2] to pre-driver stage 214 of driver110[2]; selection signal SEL[3] is set to ‘3’ (320[3]) to couple controlsignal CTRL[3] from regulator control circuit 120[3] to pre-driver stage214 of driver 110[3]; and selection signal SEL[4] is set to ‘5’ (320[4])to couple control signal CTRL[5] from regulator control circuit 120[5]to pre-driver stage 214 of driver 110[4].

Moreover, within the clock cycle starting at time T0, control circuit120[5] is going to be set to be idle, and the idle control circuit120[4] is going to be set to take place of control circuit 120[5] andgenerate a ramp signal 310[4] having the 270-degree phase. At time T0′when the ramp signal 310[5] has a falling edge, task controller 130alters the value 320[4] of selection signal SEL[4] from ‘5’ to ‘4’.Accordingly, multiplexer 212 of driver 110[4] decouple control signalCTRL[5] from, and couple control signal CTRL[4] to, pre-driver stage 214of driver 110[4]. The other value 320[1], 320[2], and 320[3] areunchanged.

Within the clock cycle starting at time T1, control circuit 120[1] isgoing to be set to be idle, and the idle control circuit 120[5] is goingto be set to take place of control circuit 120[1] and generate a rampsignal 310[5] having the 0-degree phase. Because the ramp signal 310[1]has a falling edge at time T1, task controller 130 alters the value320[1] of selection signal SEL[1] from ‘1’ to ‘5’ at time T1.Accordingly, multiplexer 212 of driver 110[1] decouple control signalCTRL[1] from, and couple control signal CTRL[5] to, pre-driver stage 214of driver 110[1]. The other value 320[2], 320[3], and 320[4] areunchanged.

Within the clock cycle starting at time T2, control circuit 120[2] isgoing to be set to be idle, and the idle control circuit 120[1] is goingto be set to take place of control circuit 120[2] and generate a rampsignal 310[1] having the 90-degree phase. At time T2′ when the rampsignal 310[2] has a falling edge, task controller 130 alters the value320[2] of selection signal SEL[2] from ‘2’ to ‘1’. Accordingly,multiplexer 212 of driver 110[2] decouple control signal CTRL[2] from,and couple control signal CTRL[1] to, pre-driver stage 214 of driver110[2]. The other value 320[1], 320[3], and 320[4] are unchanged.

Within the clock cycle starting at time T3, control circuit 120[3] isgoing to be set to be idle, and the idle control circuit 120[2] is goingto be set to take place of control circuit 120[3] and generate a rampsignal 310[2] having the 180-degree phase. At time T3′ when the rampsignal 310[3] has a falling edge, task controller 130 alters the value320[3] of selection signal SEL[3] from ‘3’ to ‘2’. Accordingly,multiplexer 212 of driver 110[3] decouple control signal CTRL[3] from,and couple control signal CTRL[2] to, pre-driver stage 214 of driver110[3]. The other value 320[1], 320[2], and 320[4] are unchanged.

Within the clock cycle starting at time T4, control circuit 120[4] isgoing to be set to be idle, and the idle control circuit 120[3] is goingto be set to take place of control circuit 120[4] and generate a rampsignal 310[3] having the 270-degree phase. At time T4′ when the rampsignal 310[4] has a falling edge, task controller 130 alters the value320[4] of selection signal SEL[4] from ‘4’ to ‘3’. Accordingly,multiplexer 212 of driver 110[4] decouple control signal CTRL[4] from,and couple control signal CTRL[3] to, pre-driver stage 214 of driver110[4]. The other value 320[1], 320[2], and 320[3] are unchanged.

Thereafter, at time T5, control circuit 120[5] is set to be idle, andthe idle control circuit 120[4] is set to take place of control circuit120[5] and generate a ramp signal 310[4] having the 0-degree phase. Attime T6′ after time T6, control circuit 120[1] is set to be idle, andthe idle control circuit 120[5] is set to take place of control circuit120[1] and generate a ramp signal 310[5] having the 90-degree phase. Attime T7′ after time T7, control circuit 120[2] is set to be idle, andthe idle control circuit 120[1] is set to take place of control circuit120[2] and generate a ramp signal 310[1] having the 180-degree phase. Attime T8′ after time T8, control circuit 120[3] is set to be idle, andthe idle control circuit 120[2] is set to take place of control circuit120[3] and generate a ramp signal 310[2] having the 270-degree phase.

Thereafter, at time T9, control circuit 120[4] is set to be idle, andthe idle control circuit 120[3] is set to take place of control circuit120[4] and generate a ramp signal 310[3] having the 0-degree phase. Attime T10′ after time T10, control circuit 120[5] is set to be idle, andthe idle control circuit 120[4] is set to take place of control circuit120[5] and generate a ramp signal 310[4] having the 90-degree phase. Attime T11′ after time T11, control circuit 120[1] is set to be idle, andthe idle control circuit 120[5] is set to take place of control circuit120[1] and generate a ramp signal 310[5] having the 180-degree phase.

As a result, each one of the regulator control circuits 120[5:1] is setto generate a control signal CTRL[5:1] corresponding to four differentphases, such as 0-degree, 90-degree, 180-degree, and 270-degree phases,in a rotational manner. Also, multiplexers 212 of drivers 110[4:1] suchthat a p-th driver is operated based on control signals corresponding toa p-th phase of the four different phases from the regulator controlcircuits 120[5:1] in a rotational manner. In the embodiment depicted inFIG. 3, each combination of regulator control circuits 120[5:1] anddrivers 110[4:1] would repeat every 20 clock cycles. Therefore, thephase errors among control signals CTRL[5:1] caused by mismatch orprocess variations of regulator control circuits 120[5:1] are evenlydistributed to drivers 110[4:1].

In the embodiment of FIG. 3, the timing for altering the values ofselection signals SEL[4:1] is set at the time when a corresponding rampsignal VRAMP has a falling edge. As such, regulator control circuits120[5:1] are switched when the PWM waveforms of control signalsCTRL[5:1] have falling or rising edges. In some embodiments, if rampsignals VRAMP are triangular wave signals, the timing for altering thevalues of selection signals SEL[4:1] is set at the time when acorresponding ramp signal VRAMP has a peak value, such as at the highestpeak or lowest peak. As such, regulator control circuits 120[5:1] areswitched when the PWM waveforms of control signals CTRL[5:1] have aknown logical value.

FIG. 4A is a graph of waveforms of various currents I[N:1] provided bydifferent drivers 110 [N:1] of a regulator circuit, such as regulatorcircuit 100 when N is set to be four (4), in accordance with someembodiments. Waveform 410[1] represents the waveform of current I[1];waveform 410[2] represents the waveform of current I[2]; waveform 410[3]represents the waveform of current I[3]; and waveform 410[4] representsthe waveform of current I[4]. After the regulator circuit is turned onand operates at a steady state (e.g., time T402), because the phaseerrors among control signals CTRL[5:1] of regulator control circuits120[5:1] have been evenly distributed to drivers 110[4:1] in atime-averaged manner, the output current from each drivers 110[4:1] hasthe same root mean square (RMS) value.

FIG. 4B is a graph of waveforms of various currents provided bydifferent drivers of a regulator circuit having a configurationdifferent from some embodiments of the present disclosure. Inparticular, the regulator circuit on which FIG. 4B is based does notrotate the use of regulator control circuits against driverscorresponding to different phases. Waveform 420[1] represents thewaveform of a current corresponding to current I[1]; waveform 420[2]represents the waveform of a current corresponding to current I[2];waveform 420[3] represents the waveform of a current corresponding tocurrent I[3]; and waveform 420[4] represents the waveform of a currentcorresponding to current I[4]. After the regulator circuit of FIG. 4B isturned on and operates at a steady state (time T404), because the phaseerrors among control signals of regulator control circuits stay withcorresponding drivers and are not evenly distributed to differentdrivers, the output current from each drivers has different RMS valuesas a result of the phase errors among control signals. In FIG. 4B,currents corresponding to waveforms 420[1] and 420[2] are in factconsuming energy rather than providing energy to the load. Thus,currents corresponding to waveforms 420[3] and 420[3] are not onlyresponsible for providing the current for the load but also forcompensating the energy consumed by the drivers of currentscorresponding to waveforms 420[1] and 420[2].

FIG. 5 is a flow chart of a method 500 of operating a regulator circuitin accordance with some embodiments. In some embodiments, method 500 isusable in conjunction with regulator circuit 100 of FIG. 1. It isunderstood that additional operations may be performed before, during,and/or after the method 500 depicted in FIG. 5, and that some otherprocesses may only be briefly described herein.

The process starts with operation 510, where N drivers 110[N:1] are setto operate based on N corresponding control signals, such as controlsignals CTRL[N:1] from N regulator control circuits, e.g., controlcircuits 120[N:1], of at least (N+1) regulator control circuits120[(N+1):1]. A p-th driver 110[p] of the N drivers is set to operatebased on one of the N control signals that corresponds to a p-th phaseof N different phases.

The process proceeds to operation 520, where another regulator controlcircuit of at least (N+1) regulator control circuits, e.g., controlcircuit 120[N+1], such that the another regulator control circuit120[N+1] generates another control signal corresponding to the p-thphase of the N different phases.

In some embodiments, operation 520 is performed by setting each one ofthe at least (N+1) regulator control circuits 120[(N+1):1] to generate acontrol signal corresponding to the N different phases, one afteranother in a rotational manner.

The process proceeds to operation 530, where the occurrence of atriggering event for task rotation is determined. In some embodiments,the triggering event for task rotation is during each clock cycle ofclock signal CLK when a corresponding ramp signal VRAMP has a fallingedge. In some embodiments, the triggering event for task rotation isduring each clock cycle of clock signal CLK when a corresponding rampsignal VRAMP has a peak value, such as at the highest peak or lowestpeak.

Responsive to the occurrence of the triggering event, the processproceeds to operation 540; otherwise, the process proceeds to operation510.

In operation 540, the p-th driver 110[p] is set to operate based on theanother control signal corresponding to the p-th phase from the anotherregulator control circuit 120[N+1].

In some embodiments, operation 540 is performed by setting multiplexers212 of the N drivers 110[N:1] such that the p-th driver 110[p] of the Ndrivers is operated based on control signals corresponding to the p-thphase of the N different phase from the at least (N+1) regulator controlcircuits 120[(N+1):1], one after another in a rotational manner.

In accordance with one embodiment, a regulator circuit includes aregulator output node, at least (N+1) regulator control circuits, and Ndrivers. N is an integer greater than 1. Each one of the N driversincludes a multiplexer, a driver stage, and a pre-driver stage. Themultiplexer includes an input port and an output port, where the inputport of the multiplexer is coupled with output nodes of the at least(N+1) regulator control circuits. The driver stage is coupled with theregulator output node. The pre-driver stage is configured to control thedriver stage based on a signal on the output port of the multiplexer.

In accordance with another embodiment, a regulator circuit includes aregulator output node, at least (N+1) regulator control circuits, Ndrivers, and a task controller coupled to the N driver and the at least(N+1) regulator control circuits. N is an integer and greater than 1.The at least (N+1) regulator control circuits are configured tovariously generate N control signals corresponding to N differentphases. A p-th driver of the N drivers is configured to provide a p-thcurrent to the regulator output node based on a control signal of the Ncontrol signals that corresponds to a p-th phase of the N differentphases, where p is an integer ranging from 1 to N. The task controlleris configured to: set the p-th driver to provide the p-th current basedon a control signal of the N control signals that corresponds to thep-th phase; set another regulator control circuit of the at least (N+1)regulator control circuits to generate another control signalcorresponding to the p-th phase; and set the p-th driver to provide thep-th current based on the another control signal from the anotherregulator control circuit of the at least (N+1) regulator controlcircuits in place of the control signal of the N control signals thatcorresponds to the p-th phase.

In accordance with another embodiment, a method of operating a regulatorcircuit includes setting N drivers to operate based on N correspondingcontrol signals from N regulator control circuits of at least (N+1)regulator control circuits, where a p-th driver of the N drivers isoperated based on one of the N control signals corresponding to a p-thphase of N different phases. N is an integer and greater than 1, and pis an integer ranging from 1 to N. Another regulator control circuit ofat least (N+1) regulator control circuits is set such that the anotherregulator control circuit generates another control signal correspondingto the p-th phase of the N different phases. Responsive to a triggeringevent, the p-th driver is set to operate based on the another controlsignal corresponding to the p-th phase from the another regulatorcontrol circuit.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A regulator circuit, comprising: a regulator output node; at least (N+1) regulator control circuits, N being an integer greater than 1; and N drivers, each one of the N drivers comprising: a multiplexer comprising an input port and an output port, the input port of the multiplexer being coupled with output nodes of the at least (N+1) regulator control circuits; a driver stage coupled with the regulator output node; and a pre-driver stage configured to control the driver stage based on a signal on the output port of the multiplexer.
 2. The regulator circuit of claim 1, further comprising: a task controller coupled with the multiplexers of the N drivers and the at least (N+1) regulator control circuits, the task controller being configured to: set the multiplexers of the N drivers such that a p-th driver of the N drivers is operated based on control signals corresponding to a p-th phase of the N different phases from the at least (N+1) regulator control circuits in a rotational manner, p being an integer ranging from 1 to N; and set each one of the at least (N+1) regulator control circuits to generate a control signal corresponding to the N different phases in a rotational manner.
 3. The regulator circuit of claim 2, wherein one of the at least (N+1) regulator control circuits comprises: a ramp generator configured to generate a ramp signal, the ramp being a triangular wave signal or a saw-tooth wave signal; and a comparator configured to generate the control signal of the one of the at least (N+1) regulator control circuits by comparing the ramp signal and an error signal generated based on a voltage level at the regulator output node.
 4. The regulator circuit of claim 1, further comprising: an error amplifier configured to generate an error signal based on a voltage level at the regulator output node and a reference voltage level, wherein the at least (N+1) regulator control circuits are configured to receive the error signal.
 5. The regulator circuit of claim 1, wherein each one of the N drivers further comprises: an inductive device between an output node of the driver stage and the regulator output node.
 6. The regulator circuit of claim 1, wherein the driver stage of one of the N drivers comprises: an upper driver coupled between an output node of the driver stage and a first power supply node, the first power supply node being configured to carry a supply voltage level; and a lower driver coupled between the output node of the driver stage and a second power supply node, the second power supply node being configured to carry a ground reference level lower than the supply voltage level.
 7. The circuit of claim 6, further comprising: an error amplifier configured to generate an error signal based on a voltage level at the regulator output node and a reference voltage level, the reference voltage level being between the supply voltage level and the ground reference level.
 8. The circuit of claim 1, wherein the N drivers are fabricated based on a first common circuit schematic; and the at least (N+1) regulator control circuits are fabricated based on a second common circuit schematic.
 9. A regulator circuit, comprising: a regulator output node; at least (N+1) regulator control circuits, N regulator control circuits of the at least (N+1) regulator control circuits being configured to variously generate N control signals corresponding to N different phases, and N being an integer and greater than 1; N drivers, a p-th driver of the N drivers being configured to provide a p-th current to the regulator output node based on a control signal of the N control signals that corresponds to a p-th phase of the N different phases, and p being an integer ranging from 1 to N; and a task controller coupled to the N driver and the at least (N+1) regulator control circuits, the task controller being configured to: set the p-th driver to provide the p-th current based on a control signal of the N control signals that corresponds to the p-th phase; set another regulator control circuit of the at least (N+1) regulator control circuits to generate another control signal corresponding to the p-th phase; and set the p-th driver to provide the p-th current based on the another control signal from the another regulator control circuit of the at least (N+1) regulator control circuits in place of the control signal of the N control signals that corresponds to the p-th phase.
 10. The regulator circuit of claim 9, further comprising: an error amplifier configured to generate an error signal based on a voltage level at the regulator output node and a reference voltage level, wherein the at least (N+1) regulator control circuits are configured to receive the error signal.
 11. The regulator circuit of claim 10, wherein one of the at least (N+1) regulator control circuits comprises: a ramp generator configured to generate a ramp signal, the ramp being a triangular wave signal or a saw-tooth wave signal having one of the N different phases set by the task controller; and a comparator configured to generate a control signal by comparing the ramp signal and an error signal generated based on a voltage level at the regulator output node.
 12. The regulator circuit of claim 9, wherein the p-th driver of the N drivers comprises: a driver stage configured to provide the p-th current; a pre-driver stage configured to control the driver stage based on a control signal corresponding to the p-th phase of the N different phases; and a multiplexer configured to couple one of the at least (N+1) regulator control circuits that generates the control signal corresponding to the p-th phase of the N different phases with the pre-driver stage.
 13. The regulator circuit of claim 12, wherein the p-th driver of the N drivers further comprises: an inductive device between an output node of the driver stage and the regulator output node.
 14. The regulator circuit of claim 12, wherein the driver stage of the p-th driver of the N drivers comprises: an upper driver coupled between an output node of the driver stage and a first power supply node, the first power supply node being configured to carry a supply voltage level; and a lower driver coupled between the output node of the driver stage and a second power supply node, the second power supply node being configured to carry a ground reference level lower than the supply voltage level.
 15. The regulator circuit of claim 14, further comprising: an error amplifier configured to generate an error signal based on a voltage level at the regulator output node and a reference voltage level, the reference voltage level being between the supply voltage level and the ground reference level.
 16. The regulator circuit of claim 9, wherein the N drivers are fabricated based on a first common circuit schematic; and the at least (N+1) regulator control circuits are fabricated based on a second common circuit schematic.
 17. A method of operating a regulator circuit, comprising: setting N drivers to operate based on N corresponding control signals from N regulator control circuits of at least (N+1) regulator control circuits, a p-th driver of the N drivers being operated based on one of the N control signals corresponding to a p-th phase of N different phases, N being an integer and greater than 1, and p being an integer ranging from 1 to N; setting another regulator control circuit of at least (N+1) regulator control circuits such that the another regulator control circuit generates another control signal corresponding to the p-th phase of the N different phases; and responsive to a triggering event, setting the p-th driver to operate based on the another control signal corresponding to the p-th phase from the another regulator control circuit.
 18. The method of claim 17, further comprising: updating p to be (p+1) if p is less than N and updating p to be one if p equals N; and perform the causing N drivers to operate, the setting another regulator control circuit, and the setting the p-th driver using the updated p.
 19. The method of claim 17, wherein the setting another regulator control circuit is performed by setting each one of the at least (N+1) regulator control circuits to generate a control signal corresponding to the N different phases, one after another in a rotational manner.
 20. The method of claim 17, wherein the setting the p-th driver to operate based on the another control signal is performed by setting multiplexers of the N drivers such that the p-th driver of the N drivers is operated based on control signals corresponding to the p-th phase of the N different phase from the at least (N+1) regulator control circuits, one after another in a rotational manner. 